Dialkoxybenzene-based compounds have widely been utilized as extremely strong electron donors in many fields and, for example, have been used as intermediates for medicament production, materials for electroluminescence displays and monomers for electrolytic polymerization and also used for production of Ziegler-Natta catalysts for orientation of polyolefins. In particular, 1,2-dialkoxy-3-fluorobenzenes such as 1,2-diethoxy-3-fluorobenzene are known to be useful as intermediates for medicament production (see WO 02/085855, WO 2004/078721, WO 2006/018955). Processes for synthesizing such compounds have been disclosed in U.S. Pat. No. 5,968,865, U.S. Pat. No. 6,124,507, U.S. Pat. No. 6,399,837 and WO 02/085855. However, in the processes described therein, 2-alkoxyphenol-based compounds are used as starting materials and are reacted with alkyl halides under a strong alkaline atmosphere to introduce other alkoxy groups. In such synthetic processes, the costs of the starting materials are high, the process yields are low, a large amount of sodium hydroxide is required, and also excess alkyl halides are generated in a large amount, so that a post-treatment step becomes troublesome. Therefore, the processes are not suitable for industrial production. Furthermore, there is known a process using 3-fluoroanisole as a starting material and through a (2-alkoxy-6-fluorophenyl) borate derivative (see JP-A-2005-314322).